The present invention relates to nonwoven wipers for industrial and other applications involving the absorption of water and/or oil.
Generally, industrial wipers must be able to quickly pick up spilled liquids, both oil based or water based, and leave a clean streak-free surface. Also, they must have sufficient capacity to hold such liquids within the wiper structure until it is desired to remove the liquids by wringing or washing. Further, they must have the strength to withstand shredding, tearing, etc. during use, and also to withstand rinsing and manual wringing. It is also desirable that they have a feel that is pleasing to the touch.
At least three types of wipers are available: paper, woven cloth or nonwoven. Paper wipers, while inexpensive, are suitable primarily for use in wiping aqueous materials and are not entirely satisfactory for use with oil. Cloth wipers, while suitable for wiping both oils and water, are expensive and must be laundered. Unless care is taken in laundering, water absorption rates for cloth wipers can be adversely affected.
Nonwoven wipers have the advantage over woven cloth wipers of being cost effective and disposable. Nonwoven wipers are made by forming filaments or fibers and depositing them on a carrier in such manner so as to cause the filaments or fibers to overlap or entangle as a web of a desired basis weight. The web is bonded by entanglement, adhesive, application of heat and/or pressure to thermally responsive fibers, or, most commonly, by a point application of heat and pressure, using patterned bonding rollers. Commonly used nonwoven manufacturing processes include carding, wetlaying and needling, spunbonding and meltblowing.
In the past, nonwoven industrial wipers have not provided the same desired performance as woven shop towels, particularly, in terms of the holding capacity for both oil and water. This problem is believed to be partially due to the bonds. At bond points produced by heat and pressure, the thermoplastic microfibers fuse together, resulting in strengthening of the web structure. However, the fusion of the fibers results in the creation of solid spots of non-absorbent thermoplastic. Not only are these spots not absorbent, but they can also act as barriers to the flow or transfer of fluid within the web. This can be particularly harmful if a line type of bonding pattern is adopted, since the lines of fused thermoplastic act as dams beyond which fluid cannot flow.
Accordingly, there is a need for an industrial nonwoven wiper which has improved oil and water capacity.